Device for keeping outbursts of fire in film projectors under local control



J. PLACHMANN DEVICE FOR KEEPING FILM PRoJEcToRs UNDER LOCAL Filed March17, 1934 OUTBURSTS OF FIRE IN CONTROL Patented July 27, 1937 PATENT OFFICE DEVICE FOR KEEPING OUTBURSTS OF FIRE IN FILM PROJECTORS UNDERLOCAL CON- TROL Josef Plachmann, Cologne, Germany- Application March 17,1934, Serial No. 716,012 In Germany March 21, 1933 6 Claims.

To prevent the iire of blazing films-which happens more especially attimes, when the lm stops motionless in front of the projecting gatefromspreading to the interior of the drums which contain the coils of film,equipment has been provided at film drum entrance and nlm drum exitwhich, by means of cutting devices, sever the blazing nlm portionbetween the drums from the film coils within the drums, and at the sametime,

10 eii'ect the closing of the drum outlets. In this way the rotating lmcoil carriers are prevented from drawing burning or smouldering iilmportions into the drums. Known devices have been equipped for thispurpose with cutters which are operated by spring action orelectro-magnets.

These cutters are released by means sensitive to temperature, forexample highly inflammable strips of iilm, which are arranged in thevicinity of the projecting gate and which in their turn are set are bythe blazing film. These illmY strips have been arranged in the shape ofa long thread slung around the projecting gate, whilst its ends weretaken to the cutting devices which are kept in the stand-by position bymeans of tension of the undamaged thread.

Devices are also known which automatically shut the projecting aperturein illm operator cabins comprising a strip of highly inflammable filmarranged in close proximity of the projecting gate and a spring operatedswitch which is fixed somewhere to the side framevoi the projectingmachine and kept in off" or no current position by means of theundamaged thread and the tension of a cord attached thereto. 'I'hedestruction of the film thread which controls the operating of thedevice causes the tension of the cord to relax, the switch operates byreleased spring action and closes a circuit of electric currentconnected to the safety devices.

All these known devices, however, are by no means free from considerabledrawbacks. For operating they rely on inflammable threads or cordsattached to inilammable threads which are connected to cutting devicesor a switch some considerable distance away. It is obvious that therebythe danger of damage to or the destruction of the thread or intermediatecord is increased and the possibility of needless operating of thesafety devices presents itself. Needless action of safety devices,however, causes most undesirable interference with the operating of theprojecting machine. Suitable covering up of the openly' stretchedinilammable thread or cord cannot avoid these disadvantages, as, in thefirst instance, covering up means the addition of constructional partsto the projecting machine, more important, however, is the fact that thestretch of cord or thread is withdrawn from indispensable observation,thus preventing the detection in time of circumstances and interferyences which hamper prompt action of the safety. devices. Furtherdisadvantages appear in the course of operating the illm projectingmachine. It is obvious and seems to the purpose to x the inflammablestrip or thread of film operating the safetydevices to the shutter ofthe projecting gate. The operating of the illm projecting machinenecessitates frequent opening-and shutting of this gate, whereby thetension of thread or strip relaxesA or tightens resulting in needlessoperating of the safety devices. Thus the known devices are bound tovcause frequent stoppages in the running of the'fllrn projectingmachine. And, finally, they necessary replacement of the inflammablethreads or cords, after destruction of temperature-sensitive meanscauses considerable loss of time, for utmost care is required forcorrect adjustment to prevent the switch or cutting devices from beingre1easedunder ordinary running conditions of the illm projectingmachine.

Disadvantages of the aforementioned description are absent with thedevice which the present invention has for object. It relates to adevice for keeping outbursts of re in nlm projecting machines underlocal control and comprises the control of cutting devices fixed in thevicinity of the nlm drums and means sensitive to temperature arranged inclose proximity of the projecting gate of the machine. The meanssensitive to temperature and the devices controlled by their influenceare, in accordance with the nature of this present invention, arrangedon a locally restricted area in the vicinity of thev film band andprojecting gate, on the gate shutter itself by preference, underabolition of all and any mechanical means for the transmission of forcesor impulses released under the iniluence of these heat-aiected means.

The present new device dispenses with all mechanical powertransmissions, as the force or impulse released by the heat-affectedmeans is transmitted by electric currents, thus, there are only electricwires leading away from the iilm projectingl gate, and, as these do nottransmit any mechanical forces, they can be conducted in such a manneras to avoid their damaging or destruction and consequent needlessoperating of the safety devices is reliably excluded.

This novel device comprises contacts to open or close electric circuitswhich former are mounted on double armed levers pivoted on a commonshaft or pin. The ends of a lever pair on one side of the pivot carry astrip of highly infiammable material under tension, whilst the leverends on the other side of the pivot have contacts mounted thereon which,after destruction of the indamrnable material and under the infiuence ofspring action or their own gravity, close an elec tric circuit. 'I'heinflammable strips consisting of film band are suitably arranged closeto the projected film immediately above and below thek projecting gateof the machine.

'Ihe cutting devices are suitably arranged in closest proximity ofthesafety channel mounted on each nlm drum.

The accompanlnyg drawing shows by way of example how the presentinvention may be performed.

Fig. l shows a sectional view of the projecting gate of afilm projectorover the line I-I of Fig. 2 and asimilar view of the film coil carryinglower drum housing with safety channel and the cutting devices arrangedlaterally thereof;

Fig. 2 shows a front view of the projectinggate with devices operated bythe burning film and releasing thereby the aforementioned cuttingdevices:

Fig. 3 shows a sectional view of Fig. 2 over the line IIL-III;

Fig. 4 shows a sectional view of Fig. 1 over the line IV--IV Fig. 5 is aside view of a projecting machine showing the disposition of the cuttingdevices and the arrangement near the projecting gate of means sensitiveto temperature.

In Figs. l-5 I is the projecting gate of a film projecting machine, 2the picture film, 3 a drum housing for the reception of the picturefilm, I and 5 are guide rolls arranged in front of guide channel lcomprising principally a channel of rectangular section through whichthe picture film is drawn.

The device for cutting the picture film comprises a supporting frame 1mounted on drum housing I. Twin tubular guides or guide cylinders 8 arefixed to this frame 1. Within bores 8 of guide cylinders 9 piston-shapedcutter holders I0 are slidingly arranged. These holders l have slots I Ifor the reception of cutter I2 which severs the` picture film 2. 'I'hecutter holders III are under the influence of spiral springs 3l arrangedbetween the cutterholders and supporting frame 1. These springs lI havethe tendency of forcing the cutter in the direction of the picture film.The cutter is guided in slots 34 of guide cylinders 9 and further guides2B; Cutter holders I0 are retained in stand by position by means ofcatches Il provided at the ends of double armed levers Il. Catches Ilpass through apertures 32 of guide cylinders 9 and engage with grooves33 provided for that purpose in cutter holders I0. Both catches are keptin that position by the pull of spiral springs I3 fixed to the oppositeends of levers I5. Double armed levers I are equipped with cross piece25 which in its turn carries a small pure iron contact plate 30. Magnetcoil 24 is fixed to supporting frame 1. The iron core l25 of said `coilopposes contact plate 30 with a very narrow space between both.

The devices effecting the release of the cutting devices are arranged,by preference, on the projecting gate shutter or picture window gate 4U,in a manner which `holds the strips of infiammable material to bedestroyed by the blazing picture film immediately above and below theprojecting gate in a very close position to the picture film. Theopening in the picture window gate frame is as shown much larger thanthe opening in the projecting gate and hence the strips of inflammablematerial may be within the former opening and yet not obscure theprojecting opening of the gate. Each one of these devices comprises twodouble armed levers I6 and I1, pivoted at IB and under the influence ofspring I9. This springJS has the tendency of forcing the opposite endsof said levers toward one another so as to cause the insulated contacts20 and 2l mounted on these lever ends to touch one another. Thismovement is prevented and the stand by position of the contacts ismaintained by a strip of highly inammable material 22, preferably ofunexpcsed film, slung around the opposite ends I6 and I1 so as to forman endless band. Contacts 20 and 2I belong to electric circuits shown inFig. 5 which cmprlse coils 24 beside a current source or supply.Contacts 20 and 2l are connected to these circuits by means of contactscrews 25.

Fig. 5 shows that a device as illustrated by Figs. 1-4 is provided foreach film drum. It will further be seen that safety devices are arrangedabove and below the projecting gate Yof the machine respectively tooperate the cutting devices.

The working of the contrivances as illustrated on the drawing iseffected in the following manner: in the case of the picture filmcatching fire in front of the film projecting gate,'the fire spreadssimultaneously to bands 22. The immediate destruction of these stripscauses the release of the lever ends in proximity of the film projectinggate and, under the influence of springs I9, the lever ends which carrycontacts 20 and 2I are forced towards each other until said contactstouch and thereby close an electric circuit conducted over coils 24 anda current source. Iron core 26 becomes magnetic and contact plate 30 oncross piece 35 connecting levers I5 is drawn towards said coil. Catch Ilbecomes by this action disengaged from grooves 33 in the cutter holders.The cutter jumps forward under the pressure of springs 3l and severs thepicture film. A lead plate 2B disposed laterally of the safety channelserves as stop for the cutter motion. As strip 22 is destroyed veryquickly, or at least relaxes its tension in extraordinarily short timeand, as the cutting devices are released by electric action, thesevering of the picture film portion between the film drums is effectedwith `extraordinary speed. The coils 2l are in serial connectionensuring simultaneous operating of both cutting devices. ri'he circuitsare arranged in such a manner that, as the diagram in Fig. 5 clearlyshows, both cutting devices operate simultaneously, even when but one ofthe inflammable strips has been destroyed.

This novel device for keeping the nre of burning picture films locallycontrolled is re-set or returned to the stand by position in the mostsimple manner by bringing the band carrying ends ofthe levers nearer toone another and fixing a new strip or band of inflammable material, ameasure which is executed within a few seconds. Thereafter, the releasedcutters are drawn back by means ci handles 21 fixed to them,

until catches I4 re-engage with grooves 33 of the cutter holders.

The new device is easily adapted to the various types of film projectingmachines, more especially to the different disposition and size of theprojecting gate shutter or projecting gate proper. In most cases it willsuflice to alter the position of pivot I8 and modify the shape andlength of the levers in order to ensure the inflammable strip ofmaterial always being held in close proximity of the picture filmimmediately above or below the lm projecting gate respectively.

Further, the cutting devices may be operated either over working currentcircuits or else over no current circuits; in the former c-ase a circuitis closed by the heat controlled switch, in the latter case it isinterrupted.

Further, the safety devices may also be worked by hand-operatedswitches, preferably push-buttons, in order to release the cuttingdevices by hand, should for some reason or other the heat controlledswitches fail to Work.

Having now described in detail the nature of this present invention andshown by way of example and accompanying drawing the manner in which itmay be performed.

I claimr- 1. Safety device for confining outbursts of fire in filmprojecting machines, comprising in combination a casing havingprojecting openings therein, a picture window gate, the picture windowof which is larger than the projecting opening of the casing anddirectly behind the same, electromagnetically operated cutting devicesfor the film in front of and behind the burning portion thereof,ignition means adapted to be .inamed from the burning film, electricswitches being automatically operated when the said :ignition means areinflamed said burning switches being arranged in a circuit wherein theelectromagnets of the cutting devices are arranged and said ignitionmeans arranged in that part of said picture window which does notregister with 'the projecting opening of the casing and immediatelyadjacent the lm moving past the picture window.

2. Safety device according to claim 1, the said cutting devices for thefilm being arranged directly in front of the opening of each lm drum.

3. Safety device according to claim 1, the said ignition switches beingarranged on the picture window gate itself.

4. Safety device according to claim 1, the said burning switchesconsisting of double-armed levers rotatable on a common axis, the armsof said levers being designed as electric contacts on the side turnedaway from the gate frame, the arms of saidl levers turned toward thegate frame being bent into the opening of the frame and adapted toreceive the ignition means, springs adapted to bring the said leversagainst forces of pressure or tension exerted by unburnt ignition meansinto the position in which they close the circuit, the electrom-agnetsof the cutting devices being arranged in the said circuit.

5. Safety device according to claim 1, the said ignition meansconsisting of film material and the picture Window gate is adapted topermit a film wound on both drums to be inserted in or removed from theprojector.

6. Safety device for confining outbursts of fire in lm projectingmachines, comprising in combination, a casing having a projectionopening therein, a picture window gate the picture window of which islarger than the projecting opening of the casing and directly behind thesame, cutting devices for the film above the projection window openingand below the projection window opening, ignition means adapted to beinflamed from the burning film, the said cutting devices beingautomatically operated on the destruction of continuity of said ignitionmeans and the said ignition means being arranged in that part of saidpicture window which does not register with the projecting opening ofthe casing and immediately adjacent the lmjmoving past the picturewindow.

JOSEF PLACHMANN.

